The Portuguese joins Swansea initially until the end of the season with the option of an extension
Ghana striker Jordan Ayew will play under coach Carlos Carvalhal following his appointment as manager Swansea City.
Player-coach Leon Britton had been in temporary charge of Swansea since the Premier League's bottom side sacked Paul Clement on 20 December.
Carvalhal was dismissed by Wednesday on Christmas Eve, with the Owls 15th in the Championship table.
The Portuguese joins Swansea initially until the end of the season with the option of an extension.
Carvalhal, the Swans' fifth permanent manager in two years, led Wednesday to the Championship play-offs in the past two seasons.
The former Besiktas, Sporting Lisbon and Maritimo boss, who succeeded Stuart Gray at Hillsborough in June 2015, had a win ratio of 42.7% from his 131 games in charge.
"We are very pleased with the appointment," said Swansea chairman Huw Jenkins.
"We felt we needed to get the managerial situation resolved as soon as possible and while the timing is not always perfect, we can look forward to the second half of the campaign with renewed optimism."
Carvalhal's first game in charge of Swansea will be at Watford in the Premier League on Saturday (15:00 GMT).
- Ghana youngster Listowell Duah scores penalty to lift trophy in Spain
- QNET marks World Health Day GHANA with wellness and heath event
- One stabbed after dispute over boundary between Danchira and Domeabra
- Ghanaian players abroad: Inaki wins trophy, Abagna, Osman, Aziz score for respective clubs
- Jeremy Doku grabs assist in Manchester City's win against Aston Villa
- Read all related articles
